Bottom sheet feeder

ABSTRACT

A sheet separating device is disclosed for separating and feeding forward the bottom sheet of a stack of sheets. It includes a feed roller covered with friction material in contact with the lead margin of the bottom sheet of the stack. A nonmoving retard member cooperates with the feed roller in a noncontacting manner to deflect the bottom sheet into a slight channel configuration and present a barrier to all other sheets. Resting on the top of the stack at the lead margin is a follower member urged against the stack. The follower is of roller configuration and freely rotatable so that as the stack is depleted, the final sheets will be dragged frictionally towards the retard member without significant frictional resistance from the follower roller, and the last sheet will have its forward feed substantially unimpeded thereby.

United States Patent [1 1 Kolibas Oct. l, 1974 1 BOTTOM SHEET FEEDER [75] Inventor: James A. Kolibas, Broadview Pmrmry Marbert Heights Ohio Assistant Exammer-Bruce H. Stoner, Jr.

Attorney, Agent, or Firm-Russell L, Root; Ray S. Pyle [73] Assignee: Addressograph-Multigraph Corportion, Cleveland, Ohio [22] Filed: July 12, 1973 [21] App]. No.: 378,782

Related US. Application Data [63] Continuation of Ser. No. 228,003, Feb. 22, 1972,

abandoned.

[52] US. Cl 271/124, 271/116, 271/167 [51] Int. Cl B6511 3/52 [58] Field of Search 271/121, 124,125,116, 271/114, 109, 37, 38, 35, 51,122,123,124, 137, 138, 167

[56] References Cited UNITED STATES PATENTS 2,368,519 l/l945 Burckhardt et al. 271/125 X 2,866,640 12/1958 Rives 271/110 3,122,040 2/1964 Bishop 271/125 X 5 7 ABSTRACT A sheet separating device is disclosed for separating and feeding forward the bottom sheet of a stack of sheets. It includes a feed roller covered with friction material in contact with the lead margin of the bottom sheet of the stack. A non-moving retard member cooperates with the feed roller in a non-contacting manner to deflect the bottom sheet into a slight channel configuration and present a barrier to all other sheets. Resting on the top of the stack at the lead margin is a follower member urged against the: stack. The follower is of roller configuration and freely rotatable so that as the stack is depleted, the final sheets will be dragged frictionally towards the retard member without significant frictional resistance from the follower roller, and the last sheet will have its forward feed substantially unimpeded thereby.

7 Claims, 4 Drawing Figures BOTTOM SHEET FEEDER RELATED CASES DESCRIPTION OF THE PREFERRED EMBODIMENT FIG. 1 illustrates a sheet feeding apparatus compris- This application is a continuation of my copending 5 ing sheet holder means able to hold a stack of application Ser. No. 228,003 filed Feb. 22, 1972, now abandoned.

BACKGROUND OF THE INVENTION This invention relates to sheet feeding apparatuses and more particularly to apparatuses for feeding the bottom sheet of a stack.

The prior art has known many types of bottom sheet feeders varying in structure from the very simple to the very complex. The complex bottom sheet feeders although reliable, were in general large, bulky and expensive. In addition, the complex bottom sheet feeders were not readily adaptable to existing equipment. The simple bottom sheet feeders known to the prior art were not reliable and exhibited problems such as double feeding and the like. In particular, folded letters, at or near the top of a stack, will tend to jam most feeders due to their tendency to unfold. Therefore, an object of this invention is to produce a bottom sheet feeder apparatus which is simple and of low cost; and capable of feeding paper after the paper has been folded by capturing and holding the lead edge of the sheet stack.

Another object of this invention is to produce a bottom sheet feeder apparatus which is reliable.

Another object of this invention is to produce a bottom sheet feeder apparatus which is easily mounted on existing machines.

Another object of this invention is to produce a bottom sheet feeder apparatus which is easily disengaged from the machine when manual feed is desired.

SUMMARY OF THE INVENTION In order to attain the foregoing objects, there are provided first and second coaxial wheels driven in a sheet feeding direction and spaced apart and a retard member or separator projecting between the wheels and having two specifically related sloping bottom surfaces causes the sheets to abut and retard, but deflects a portion of the bottom sheet downwardly if unsupported by another sheet below as fed forward. A weighted surface, such as a large wheel, rides the top of the stack of sheets at the leading margin and turns only when the top sheet of the stack reaches the high point of the first of the sloping bottom surfaces and is dragged forward beneath the retard member.

Other objects and a fuller understanding of the invention may be had by referring to the following description and claims, taken in conjunction with the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is the preferred embodiment of the invention showing a side sectional view together with auxilliary feed wheels, such as the input feed rollers of a duplicating machine imaging device;

FIG. 2 is an enlargement of a portion of the apparatus shown in FIG. 1 with a full supply of sheets to be fed;

FIG. 3 illustrates the condition after the stack has been fed to the last few sheets; and

FIG. 4 is a view taken on line 4-4 of FIG. 3.

sheets, first and second feeder means 11 and 12, respectively, and a retard means 46. The first feeder means 11 includes first driving means 13 which is illustrated in FIG. 1 as a forwardly driven override clutch which will drive paper sheets, but. will allow the outer drive surface to exceed the speed of its drive shaft whenever an exterior force is applied, such as when a sheet of paper separated from the stack is grasped by another set of drive wheels and pulled away at a speed greater than when driven by the means 13. The first driving roll means 13 includes first and second driving surfaces 21 and 22, respectively. The first sheet feeder means 11 also includes first pressure means 14 which is illustrated as a pressure roll means which is able to rotate about an axis 38 and is urged by urging means 36 to press upon a paper stack placed on holder 10. Roll members 14 are not directly driven, and simply ride the stack of sheets in a static condition. When the stack is reduced to the extent that the top sheet drops below abutment 28, then the roll members rotate slightly with, and under drive from, the moving sheet.

In order to illustrate the capability of the feeder to operate with another processing machine, the intake feeder of a representative device is shown as a second feeder means 12. The second feeder means 12 includes a second driving means 16 which is also illustrated as a driving roll means having a first and a second driving surface 23 and 24, respectively. The second driving means 16 is able to rotate about an axis 39. The diameters of the first and second driving surfaces 23 and 24 are shown as being substantially different. Consequently, the ratio of the diameter of the first driving surface 23 to the diameter of the second driving surface 24 of the second driving roll means 16 is materially greater than the ratio of the diameter of the first driving surface 21 to the diameter of the second driving surface 22 of the first driving roll means 13. The second feeder means 12 includes second pressure means 17 which is shown as pressure roll means 17 rotatable about an axis 43 and which is engageable with the first driving roll means 16 to feed sheets therebetween. Although the driving means 13 and 16 and the pressure means 14 and 17 in the first and second feeder means 11 and 12 have been illustrated as rolls, equivalent structures such as driving belts, driving surfaces and the like are included within the definitions of driving means and pressure means.

Separation is assured by causing the bottom sheet of a supply stack to buckle downwardly, and the sheets immediately above to advance a short distance and be restrained as the bottom sheet advances. These functions are produced by portions of an element or retard member 46, which for convenience may be termed a retard member. Member 46 is slida'ble within a housing 47 and adjustable by a screw 48, and may be spring loaded, as by spring 44, for larger range of intermixed thicknesses and weights of paper. The housing 47 is connected to a structure 50 which structure is fixed relative to the sheet holder means 10. The housing 47 can be rotated about an axis 49 to disengage the sheet feed ing apparatus when manual feeding is desired. The retard member 46 has a vertical abutment wall 28 and carries as a part thereof a foot 29 to cooperate with the first feeder means 11 and the sheet holder means to separate the bottom sheet of a stack. The lower portion of the foot 29 exhibits two surfaces each forming an acute angle relative to the sheet holder means 10 with the vertex thereof pointing in the direction of feed which is to the left in FIG. 1.

The sheet feeding apparatus shown in FIG. 1 includes power means 52 which drives the first driving means 13 at a substantially less sheet-feeding speed than the second driving means 16. In this embodiment the power means includes the axis 59 of the first driving means 13 being mounted on carrier means 60. The power means 52 also includes idler roll means 26 having an axis 61 mounted on the carrier means 60. The axis 61 of the idler roll means 26 is able to move relative to the first driving means 13 as indicated by the slot 62. Urging means 63 is connected between the carrier means 60 and a support 64 which support is fixed relative to the sheet holder means 10. The urging means 63urges the idler roll means 26 to engage the second driving surfaces 22 and 24 of the first and second driving means 13 and 16, respectively. The power means 52 includes motive means 57 shown as a motor connected to a pulley 55. The pulley 55 is mounted upon a transfer roll 54 which is in contact with the first driving surface 23 of the second driving means 16. The difference in diameters of the respective first and second driving surfaces of the first and second driving means 13 and 16 causes the first feeder means 11 to have a substantially less sheet feeding speed than the second sheet feeder means 12.

The apparatus shown in FIG. 1 includes clutch means 65 shown in FIG. 2 to disengage the first feeder means 1 1 to allow the first feeder means 11 to move at a sheet feeding speed commensurate with the sheet feeding speed of the second feeder means 12 when a sheet is being engaged by the first and second feeder means 11 and 12 simultaneously. The clutch means 65 includes clutch means installed between the first driving surface 21 and the power means 52. FIG. 2 illustrates a particular structure of a suitable clutch means 65 wherein a one-way clutch means is installed between the first and second driving surfaces 21 and 22 of the first driving roll means 13.

A first switch means 71 having a sensor 73 is connected to a control means 58 through a conductor 74. A second switch means 72 having a sensor 75 is connected through a conductor 76 to the control means 58. The control means 58 is connected to the motor 57. When a stack of sheets is placed on the sheet holder means 10, the sensor 75 is depressed activating switch 72 and the control means 58. The control means 58 energizes the motor 57 which rotates the second driving roll means 16 at a sheet feeding speed substantially greater than the first driving roll means 13. The movement of the first driving roll means 13 in cooperation with the first pressure means 14 causes the bottom several sheets of a stack of sheets to abut against the foot 29 allowing only the bottom sheet to be conveyed by the first driving roll means 13. The bottom sheet is conveyed to the second feeder means 12 wherein the second driving roll means 16 conveys the bottom sheet at a substantially greater sheet speed than the first driving roll means 13. The clutch means 65 allows the first driving surface 21 to override and in effect disengage from the motor 57 to allow the first driving surface. which is in contact with the bottom sheet, to move at a speed commensurate with the sheet feeding speed of the second driving roll means 16. After the bottom sheet has been fed by the second feeder means 12, the first switch means 71 and the control means 58 deactivate the motor 57. This can be accomplished by having the sensor 73 of the first switch means 71 responsive to the trailing edge of the bottom sheet or having the sensor 73 responsive to the leading edge of the following sheet. The differential in sheet feeding speed between the first feeder means 11 and the second feeder means 12 insures that the sheet is accelerated so that a gap will be present between the trailing edge of the first bottom shset and any subsequent sheet.

FIG. 2 illustrates an enlarged view of the first feeder means 11 comprising the first driving roll means 13, the first pressure means 14 and the retard member 46. A stack of sheets 80 is held by the sheet holder means 10 and comprises a bottom sheet 81, a second sheet 82 and a third sheet 83 plus static sheets thereabove.

Intersheet forces exist between adjacent sheets in the stack and tend to keep the sheets together making sheet separation difficult. The intersheet force can include static and dynamic frictional forces in addition to electrostatic and adhesive forces and the like.

The first driving roll means 13 rotates about the axis 59 in a counterclockwise direction as indicated by the arrow 77. The first driving surface 21 is connected to the second driving surface 22 through the clutch means 65. The clutch means includes a first driving surface ring 67 being connected to the first driving surface 21 and a second driving surface ring 68 being connected to the second driving surface 22. The region between the first driving surface ring 67 and the second driving surface ring 68 comprises six portions 121-126 each having a distance therebetween which is tapered from one end of the portion to the other. Each portion has a bearing which is free to move within the respective portion. When the second driving surface 22 is rotated by the idler roll means 26, the second driving surface ring 68 rotates as indicated by the arrow 66. The movement of the second driving surface rings 67 and 68 are shown in positions 121A-l26A to engage the first driving surface 21 and cause it to rotate at the same angular speed as the second driving surface 22. When the bottom sheet 81 is simultaneously engaged with the first and second feeder means 11 and 12, the accelerated movement of the bottom sheet 81 rotates the first driving surface 21 at a greater angular speed than the second driving surface 22 causing the bearings to move into the phantom positions 121Bl26B wherein the bearings are no longer simultaneously abutting against the first and second driving surface rings. The movement of the bearings to the phantom positions 121B126B disengages the first driving surface 22 to allow the bottom sheet 81 to move at a speed commensurate with the sheet feeding speed of the second feeder means 12.

The foot 29 is composed of a primary surface 106 (FIG. 3) and a secondary surface 107. The primary surface 106 forms an acute angle relative to the stack of sheets in proximity to the leading edge thereof in the order of 40. The secondary surface 107 forms an angle relative to the sheet holder means 10 of approximately 5 which is the angle at which the bottom sheet 81 leaves the first feeder means 11 and thus serves as a guiding surface for the sheet during departure. The first driving roll means 13 has a profile which is in the form of an arc. The profile of the foot 29 intersects the aforesaid arc of the first driving roll means 13. The foot 29 engages with the top surface of the bottom sheet 81 to cause the bottom sheet 81 to bend at a point 111 in the direction of sheet conveyance. The extended departure guiding surface 107 of the foot perpetuates this bend, resulting in a significant degree of wrap of the lowermost sheet about the driving roll means 13. As such it may be termed a departure guide means" for the above purpose, and while it has been shown as integral with foot 29 of the retard member 46, it will be appreciated that a guide surface independently supported and similarly directed would serve the purpose equally well.

FIG. 2 illustrates a first and a second friction means 101 and 102, respectively, wherein the first friction means 101 includes the first driving surface engaging the bottom surface of the bottom sheet 81. The second friction means 102 includes the foot 29 engaging with the top surface of the bottom sheet 81 and also engaging with the second and third sheets 82 and 83. The second friction means 102 has a friction coefficient with paper of a value less than that of the first friction means 101 yet greater than the intersheet force be tween adjacent sheets. The intersheet forces cause the second and third sheets 82 and 83 to be conveyed by the movement of the bottom sheet 81. The relationships among the first friction means 101, the second friction means 102 and the intersheet forces cause the second and third sheets 82 and 83 to abut against the primary retard surface 106 and cause only the bottom sheet 81 to be conveyed by the first driving roll means 13.

FIG. 4 is a view taken on line 4-4 of the enlargement shown in FIG. 2. The first driving means 13 includes the first and second driving surfaces 21 and 22 wherein the first driving surface 21 includes the first and second driving elements 91 and 92, respectively. The retard member 46 includes the foot 29 the latter being interdigitated with the first and second driving element means 91 and 92, spaced in such a manner as to allow the bending and escapement of a wide variety of paper weights and thicknesses. In the illustration shown in FIG. 4 there are two driving element means 91 and 92 and a single foot 29. The first pressure means 14 is illustrated in FIG. 4 as two pressure roll means corresponding to the first and second driving element means 91 and 92. The leading edge of the bottom sheet 81 is illustrated as 81A whereas the trailing edge of the bottom sheet 81 is illustrated as 81B. The separator means 29 extends between the first and second driving element means 91 and 92 to cause the bottom sheet to be bent in a direction transverse to the direction of conveyance, forming a shallow channel extending in the direction of feed. The cooperation between the first feeder means 11, the retard structure 46 and the sheet holder means 10 separate and bend the bottom sheet in two directions as shown in FIGS. 2, 3 and 4 to insure that a single sheet will be conveyed by the first feeder means 11.

Since the sheet is engaged and separated at the center of the lead edge of the bottom sheet, the sheet is driven and transported forward with high frictional forces by elements 91 and 92 but with no lateral or side to side forces exerted on the sheet thereby allowing the alignment of the sheet being fed to be controlled by simple side guides before entering a second transport means.

The sheet feeding apparatus shown in FIGS. 1-4 can be installed on many existing machines. In many cases the second sheet feeder means 12 is an existing part within the structure of the machine. In such a case, only the addition of the idler roll means 26, the first feeder means 11 and retard member 46 need be installed. In addition, after installation the apparatus can be disengaged by rotating the housing 47 about axis 49 to allow manual feeding through the second feeder means 12.

The foregoing specification discloses a simple and highly reliable sheet feeding apparatus that can be manufactured and installed at a low cost. The apparatus contains all the advantages of .a bottom sheet feed ing apparatus without the size and complexity of the apparatuses of the prior art.

The wheel 14 turns only with a stack whose height is not sufficient to reach the uppermost point of surface 106. The bottom sheets will tend to drag forward to contact surface 106, but the sheets above will only move in a vertical direction. After the stack has been reduced to the condition shown in FIG. 3, the rotatable mounting of wheel 14 shows its merit. A stationary weight will introduce a retard function. Wheel 14 will rotate slightly as it holds the remainder sheets tightly to the surface 21, and allows them to advance until they are in contact with surface 106. It will also rotate freely as the last sheet of the stack is fed forward in its turn.

The novel roll-weight action of roll 14 provides a feeder that can accommodate a mixture of sheets of a wide variety, and is not caused to malfunction by folded or thin sheets.

What is claimed is:

1. An apparatus for feeding one sheet at a time from the bottom of a stack of sheets on a support surface which comprises:

a feed roller member covered with high coefficient frictional material for contact with the lead margin of the bottom sheet of the stack;

means for driving the feed roller member in a sheet feeding direction;

a retard member, non-moving in the direction of sheet travel, disposed above the axis of the feed roller member, cooperating in a non-contacting manner with the surface of the feed roller member, and having a lead-in side so configured as to provide a stop for the lead edge of the stack directly above the feed roll member and sloped to guide a portion of the leading edge of the fed bottom sheet below the feed roller surface with a degree of overlap therewith sufficient to deflect each fed sheet into a slight channel configuration about one of said members as the fed sheet passes therebetween, said retard member presenting surfaces blocking all sheets of a stack other than the bottom sheet from being fed forward by the feed roll member;

follower means mounted adjacent the retard member at the lead-in side thereof and urged toward the feed roll member axis so as to make contact with the top of a stack of sheets on the support surface at the lead margin thereof when the latter is against said blocking surfaces to press the lead margin of the bottom sheet of such stack against the surface of the feed roller member, and also acting to urge the sheets of said stack into frictional driving relationship with each other whereby to urge the final sheets of a stack into operative contact with said guide configuration of said retard member to insure proper feeding thereof as the stack approaches depletion.

2. An apparatus as set forth in claim 1 in which the feed roller member projects substantially above the support surface holding the stack, and in which there are departure guide means leading away from the point of conjunction of the feed roller member and the retard member in the general direction of feed, said departure guide means having a direction bending the sheet towards the support surface and producing thereby a partial wrap of the fed sheet about the surface of the feed roller member.

3. An apparatus as set forth in claim 1 in which the feed roll member is driven through an overrunning clutch whereby a sheet being fed can be carried away at a higher speed than that determined by the drive for the feed roll member.

4. An apparatus as set forth in claim 1 in which one of said members is resiliently urged towards the other to permit self adjustment of the degree of overlap between said members in response to sheet stiffness to thereby accommodate sheets of varying ranges of stiffness in a single stack.

5. An apparatus as set forth in claim 1 in which said follower means comprises a roller and includes means mounting the roller for free rotation so as to form a nip with the feed roller member as the stack approaches depletion, said roller avoiding any tendency of the follower means to resist sheet motion in a feeding direction, and allowing the last sheet to be fed forward with minimum follower restriction.

6. An apparatus as set forth in claim 5 in which the feed roller member projects substantially above the support surface holding the stack, and in which there are departure guide means leading away from the point of conjunction of the feed roller member and the retard member in the general direction of feed, said departure guide means having a direction bending the sheet towards the support surface and producing thereby a partial wrap of the fed sheet about the surface of the feed roller member.

7. An apparatus as set forth in claim 5 in which one of said members is resiliently urged towards the other to permit self adjustment of the degree of overlap be tween said members in response to sheet stiffness to thereby accommodate sheets of varying ranges of stiffness in a single stack. 

1. An apparatus for feeding one sheet at a time from the bottom of a stack of sheets on a support surface which comprises: a feed roller member covered with high coefficient frictional material for contact with the lead margin of the bottom sheet of the stack; means for driving the feed roller member in a sheet feeding direction; a retard member, non-moving in the direction of sheet travel, disposed above the axis of the feed roller member, cooperating in a non-contacting manner with the surface of the feed roller member, and having a lead-in side so configured as to provide a stop for the lead edge of the stack directly above the feed roll member and sloped to guide a portion of the leading edge of the fed bottom sheet below the feed roller surface with a degree of overlap therewith sufficient to deflect each fed sheet into a slight channel configuration about one of said members as the fed sheet passes therebetween, said retard member presenting surfaces blocking all sheets of a stack other than the bottom sheet from being fed forward by the feed roll member; follower means mounted adjacent the retard member at the lead-in side thereof and urged toward the feed roll member axis so as to make contact with the top of a stack of sheets on the support surface at the lead margin thereof when the latter is against said blocking surfaces to press the lead margin of the bottom sheet of such stack against the surface of the feed roller member, and also acting to urge the sheets of said stack into frictional driving relationship with each other whereby to urge the final sheets of a stack into operative contact with said guide configuration of said retard member to insure proper feeding thereof as the stack approaches depletion.
 2. An apparatus as set forth in claim 1 in which the feed roller member projects substantially above the support surface holding the stack, and in which there are departure guide means leading away from the point of conjunction of the feed roller member and the retard member in the general direction of feed, said departure guide means having a direction bending the sheet towards the support surface and producing thereby a partial wrap of the fed sheet about the surface of the feed roller member.
 3. An apparatus as set forth in claim 1 in which the feed roll member is driven through an overrunning clutch whereby a sheet being fed can be carried away at a higher speed than that determined by the drive for the feed roll member.
 4. An apparatus as set forth in claim 1 in which one of said members is resiliently urged towards the other to permit self adjustment of the degree of overlap between said members in response to sheet stiffness to thereby accommodate sheets of varying ranges of stiffness in a single stack.
 5. An apparatus as set forth in claim 1 in which said follower means comprises a roller and includes means mounting the roller for free rotation so as to form a nip with the feed roller member as the stack approaches depletion, said roller avoiding any tendency of the follower means to resist sheet motion in a feeding direction, and allowing the last sheet to be fed forward with minimum follower restriction.
 6. An apparatus as set forth in claim 5 in which the feed roller member projects substantially above the support surface holding the stack, and in which there are departure guide means leading away from the point of conjunction of the feed roller member and the retard member in the general direction of feed, said departure guide means having a direction bending the sheet towards the support surface and producing thereby a partial wrap of the fed sheet about the surface of the feed roller member.
 7. An apparatus as set forth in claim 5 in which one of said members is resiliently urged towards the other to permit self adjustment of the degree Of overlap between said members in response to sheet stiffness to thereby accommodate sheets of varying ranges of stiffness in a single stack. 